This candidate for a Physician Scientist Award proposes an organized, five year program of didactic study and supervised research in human genetics, genetic epidemiology and developmental neurobiology, particularly as these areas apply to schizophrenia and childhood pervasive developmental disorder. In Phase I of the award, the PI will participate in a formal didactic experience in the Department of Epidemiology of the Johns Hopkins University School of Hygiene and Public Health. This experience will be oriented towards specialization in the major programmatic area of Human Genetics/Genetic Epidemiology with additional course work in biostatistics, molecular genetics and neuroscience. Supervised development and piloting of instruments for use in the proposed research studies will take place in the initial two years of the award. With such training the PI will have the opportunity to master specific research methods, and develop a fundamental knowledge base in human genetics, genetics, genetic epidemiology and neurobiology. This will be essential for the implementation of the research component of this award, as well as for his future independent research efforts in psychiatric genetics. In Phase II of the award, the focus will be on the development of a comprehensive research project concerned with defining the neuropsychiatric, developmental and neurobiological variables associated with the fragile X genetic abnormality. It is hypothesized that the study of individuals with the fragile X genetic abnormality will confirm the presence of a specific neuropsychiatic phenotype: pervasive developmental disorder in male hemizygotes, and schizophrenia spectrum disorders in female heterozygotes. It is proposed that the information gained from this research will improve the understanding of the genetics, neurobiology and treatment of schizophrenia spectrum disorders and pervasive developmental disorders in the general population. The course of study and research proposed by this candidate will lead to academic specialization in the fields of psychiatric genetics, neurogenetics and genetic epidemiology. Combined with his extensive clinical training, this will provide him with the necessary skills to develop and conduct independent clinical and neurobiological research in these areas, particularly, with respect to the genetics of schizophrenia and childhood pervasive developmental disorder.